The present disclosure relates to a novel Robotic Strong Arm (RSA) and device to aid in the transfer of people with disabilities to and from their wheelchairs or electric powered wheelchair onto other surfaces.
There are approximately 1.5 million people in the United States who have disabilities that require them to use a wheelchair. One study found that 60% of people reported shoulder pain since beginning their wheelchair use. In comparison, only about 4.7% of the general population report regular shoulder pain. Sitting pivot transfers (SPTs) are ranked among the most strenuous daily tasks of wheelchair users. Repetitions of this task over time can be detrimental for the shoulder and elbow joints of wheelchair users.
Biomechanics
There are variations in wheelchair users' movements when transferring themselves depending on their level of injury. When a patient transfers him/herself from a wheelchair to another surface, most of their weight is initially supported by their trailing upper extremity (U/E). As they lose contact with the seat, weight is shifted to the leading U/E. During wheelchair transfers, large forces are placed on the shoulder and elbow joints. The leading shoulder encounters higher displacement and velocities than the trailing one. This can cause damage in the leading arm to be accelerated and the onset of pain in this arm to occur sooner.
When wheelchair users are transferred by other people, the biomechanics of the transfer take on a different form. Strain is still placed on the wheelchair-users shoulder joints, although it is more evenly distributed across the sagittal plane. There is also an additional factor of strain placed on the lower back of the person assisting with the transfer. One study found that a pivot transfer puts 112 lbs of force onto the clinician assisting with the transfer and raises their risk of developing a lower back disorder to 38.8%.
Injuries
Between 1973 and 1987, 770 wheelchair-related accidents that led to death were reported to the U.S. Consumer Products Safety Commission. 8.1% of these accidents were caused by falls during transfers. Between 1986 and 1990, there were an estimated 36,000 wheelchair-related accidents in the U.S. that resulted in a visit to the emergency department. 17% of these accidents were due to falls during transfers. In 2003, more than 100,000 wheelchair related injuries were treated in U.S. emergency departments, showing an upward trend in the number of injuries over time.
When wheelchair users are transferred by other people, there is an additional risk of injury to the caretaker. In one study, of the 48 accidents reported by the 174 participants, 15.5% involved attendants. There were more than 1,325,000 home care workers or clinicians in the United States in 2004. This group is expected to grow by 56% from 2004 to 2014. Lower back injuries are a major risk for this group, and one estimate found that 10.5% of back injuries in the United States are associated with transferring patients. In one study investigating bed to chair transfers, it was found that healthcare workers experience up to 3500N of compressive forces during a single transfer. In another study where lifts were implemented in a hospital to assist with patient transfers, it was found that over a 3 year period, there was a 70% decrease in claims cost at the intervention facility. The cost of compensation for injuries at this facility also decreased, with a 241% increase in the comparison facility.
Lifts
One technique that is used in many healthcare facilities is to move patients around using ceiling-lifts. In one study where lifts were added to an extended care unit, 71.4% of care staff reported that it became their preferred method of transferring patients and 96% believed that the ceiling lifts made lifting residents easier. While these lifts effectively transfer people without placing as much strain on the caretaker, they are often not used because they are time-consuming. In many cases, legislation concerning the implementation of lifts is focused on the caretakers' comfort and safety as opposed to the patients'. In rare cases, these lifts can even subject the patient to bruising or skin tearing. Another major concern when transferring patients using a lift system is that the patient may feel that being moved around in such a manner is undignified.
High-Tech Devices
Few high tech devices are report in the literature. One such device is the Home Lift, Position, and Rehabilitation chair (HLPR) is currently being developed and will be able to lift a patient, rotate, and place him/her on a toilet, chair, or bed. However, this chair is meant for home use only and an incline of 10 degrees can cause tipping.
The transfer device market is populated by well-established players with products that have been available for a long time. Patient lifts are the most common type of lift that are characterized by having 4 caster wheels, 2 long legs, and a lift arm that is operated using a manual or powered hydraulic jack. The person is placed in a sling, hoisted vertically with the lift arm. Two well-known manufactures of this type of device are Hoyer and Invacare. Another type, more typical of institutional settings (and some highly modified homes), is the overhead lift. This type of lift system utilizes a track or gantry rail system mounted to the ceiling over a strategic area, such as a bed or bathroom, which a winch unit travels on. The person is placed in a sling, they are hoisted by the winch, and the care giver moves them about on the track or gantry.
Numerous other types of devices, ranging from low tech to high tech, exist for aiding with transfers. On the low tech side, transfer boards which are a short piece of smooth laminated wood that can be placed between person's chair and the surface they are transferring to or from. The caregiver then slides (often more like dragging) the person across board and onto the destination surface. Some devices are highly specialized. The Hover Jack (Hover Tech International) is an inflatable cushion that is specifically designed to aid a caregiver in lifting people off the floor and into a bed. There are many styles of chairs that specifically designed to help lower people in an out of bath tubs. On the high tech side is Panasonic's transfer assist robot (http://www.youtube.com/watch?v=LBMJCI-FzrM), which acts much like a forklift for moving people.